1. Field of the Invention
This invention relates to a structure of a cross arm for use in a pushbutton tuner and more specifically to improvements in a cross arm having a relatively simple structure and capable of not only appropriately holding a frequency setting member but of also preventing it from being locked too early.
2. Description of the Prior Art
In general, a cross arm for use in a pushbutton tuner has a structure in which a frequency setting plate pivotally mounted on the cross arm is to be properly locked to carry out the tuning by pushing a pushbutton. Such frequency setting plate has to be released from its locked condition for changing its setting. However, when the frequency setting plate has been turned and is to be locked again by pushing the pushbutton from its released condition, if the frequency setting plate is locked before the pushbutton is sufficiently pushed in, a so-called "early lock" occurs. Therefore, a predetermined tuning condition previously made by a manual tuning axis is apt to be modified and thus the proper tuning relation cannot be kept.
That is, in order to lock the frequency setting plate pivotally mounted on the cross arm, there is provided a pressing member which is pushed in by slidable operation of the pushbutton. On the other hand, an early lock preventing plate is provided so that the frequency setting plate which has been released from the pressing member may not be re-locked by the pressing member until the pushbutton is sufficiently pushed in to thereby incline the frequency setting plate to a predetermined angle by means of a rotatable crank.
However, the conventional mounting structure of such frequency setting member has been one of caulkings by means of bolts and nuts or rivets, and accordingly, such early lock preventing plate other than the above caulking parts has been also fixed on the cross arm. Such conventional structure has such drawbacks that machining of parts around the frequency setting member has been made complicated and a relatively large number of parts are required, whereby it is made difficult to keep the proper operational relations between the many parts.